Lift truck



Jan. 16, 1962 w. A. WILLIAMSON LIFT TRUCK 3 Sheets-Sheet 1 Filed DeC.29, 1958 INVENTOR.

WILLIAM A. WILLIAMSON 3y/IWW ATTORNEY.

Jan. 16, 1962 w. A. WILLIAMSON LIFT TRUCK 3 Sheets-Sheet 2 Filed Dec.29, 1958 INVENTOR.

WILLIAM A. WILLIAMSON ATTORNEY.

Jan. 16, 1.962

Filed Dec. 29, 1958 FIG. 3

DRIVE MOTOR ARM. m |9/"j [48m IGS/- W. A. WILLIAMSON LIFT TRUCK fno 5P266 I l I26 3 Sheets-Sheet 3 IN VENTOR.

WILLIAM A. WILLIAMSON ATTORNEY nite rates ice 3,016,973 LHT TRUCKWilliam A. Williamson, Battle Creek, Mich., assigner to Clark EquipmentCompany, a corporation of Michigan Filed Der. 29, 1955, Ser. No.'783,364 12 Claims. (Cl. R52- 14) This invention relates to lift trucksand more particularly to a lift truck providing a remote operatorstation located on a lifting platform of the truck and from which thetruck can be controlled.

Lift trucks of the type contemplated are particularly useful fortransporting and locating in elevated position inside of buildingsworkers who are responsible for maintenance of elevated building Xtures,utilities, machinery and the like, and for the accurate spotting ofmaterials in elevated bins, racks and the like.

It is an important object of the present invention to provide a lifttruck which is controllable in all of its functions by an operatorlocated remotely on a lifting platform of the truck.

It is another object of the invention to provide a remote controloperator station on the lifting forks of a lift truck from which anoperator can control forward and reverse movement of the truck, cansteer the truck, can control lifting and lowering of the station on theextensible upright of the truck, and can operate braking mechanism ofthe truck.

lt is a further object of the present invention to provide controlmechanism in a lift truck of the type contemplated both at a remotecontrol station on the lifting forks of the truck and at a locationconventional in such trucks, said control mechanism at the remotestation providing safety features relative to operation of the travel,lift, and steer functions of the truck.

A still further object of the invention is to provide improved alternatesteering systems for steering the truck from a normal or from a remotelocation on the truck.

A feature of the invention is to provide a remote drive control for thetruck which limits the available speed of the truck in a forwarddirection below the speed available when the truck is driven from theconventional operators station.

Another feature of the invention provides a connection between theremote forward and reverse drive control means and remote lifting meansso that the truck can be driven in forward or reverse only when thelifting forks or platform is below a predetermined height in theupright.

of this invention will appear to those familiar with the art from thefollowing detailed description and with reference to the accompanyingdrawings.

In the drawings:

FIGURE l is a perspective view of my lift truck taken from the rear,starboard quarter of the truck and showing an operator located at theremote control station in elevated position;

FIGURE 2 is a somewhat schematized plan view of the truck structureshown in FIGURE l, with the remote operators station removed from thelifting forks;

FiGURE 3 is a schematic wiring diagram of the remote and conventionalcontrols of the truck; and

FlGURE 4 is a sectional view taken along line 4--4 of FGURE 2, saidsection being rotated 90 counterclockwise.

Referring now in detail to the drawings, there is illustrated generallyat numeral a straddle stacker type industrial truckV which includes atractor unit indicated generally at numeral l2, a load carrying unit ortrailer frame indicated generally at numeral 14, and a remote controloperator station and article handling attachment The above and furtherobjects, features, and advantages associated with the trailer frame andindicated generally at numeral 16.

The tractor unit comprises a powerhead 1S, which includes an electricdrive motor (illustrated schematically in FIGURE 3 at 19) mounted indriving association with the traction wheel 2t) and adapted to receiveelectrical energy from a battery unit located within a batterycompartment 22, and a truck control and steering handle 24, which isoperatively connected to the traction wheel and the drive motor forturning same in a horizontal plane to steer the truck and which includesan operator control box 26 for operating the truck in forward or reversedrive, for lifting and lowering the forks or platform with which theremote control station 16 is associated and for operating solenoidactuated brake (not shown) associated with the drive motor i9. Ahydraulic pump and motor combination and suitable electric and hydrauliccontrol units, cables, hoses and the like (shown in part in FIGURE 3)are all mounted on a battery compartment 22 of the tractor unit l2,being operatively connected to the control box 26 of the steer handle24, to control lifting and lowering movements of the remote station 16as will be explained in detail hereinafter. The battery compartment 22is mounted upon a platform 27 which is spaced above and is parallel to aplatform 28 of tractor unit 12.

The load carrying unit or trailer frame 14 comprises generally aU-shaped frame 29 having a pair of Outrigger straddle arms 3i? connectedat one end to a telescoping upright or mast 32. The entire frame 29 issupported on, first, two caster wheels 34 (one of which is shown in FIG-URE 1) connected to the mast 32 by a pair of horizontally disposedplates 3l suitably connected tol the mast 26, extending in a directionopposite to the Outrigger arms Sti and partially encompassing the frame2S of the truck unit, and, second, a pair of trail wheels 36 adjacentthe outer ends of the Outrigger arms 3G.

Centrally of the U-shaped frame 29 and the mast 32 is a lifting unit 38of the remote control station 16. The lifting unit comprises a pair oftines all connected at one end by a cross member 42 which, in turn,cooperates and is suitably connected in known manner to sprocket chains44, sprockets 46, a power lift piston 43 and roller arrangements Stl and52 cooperating in channels, such as illustrated in plan in FIGURE 2, allof which are operated by the aforesaid hydraulic pump and motorcombination to raise and lower the tines 40 relative to the mast 32 whendesired.

The tractor unit 12 `and trailer unit 14 are connected to each other byan articulating coupling means, indicated generally at numeral 56. Thecoupling comprises gene-rally a connecting plate 58 attached to the:opposite sides of the mast 32 by means of a pair of forwardly extendingplate members 69 and having connected to the one surface thereof a pairof laterally spaced and outwardly opening vertical channel members 62and a centrally disposed rearwardy opening channel member 64. A pair oflaterally displaced, longitudinally extending frame members 66 areconnected together by means of a vertically extending concave connectingplate 68, and are also secured between the platforms 2,7 and 28. Each offrame members 66 includes a vertically extending section at the forwardend thereof supporting a pair of rollers 7@ which are mounted forvertical movement in the corresponding channel members 62, whereastransverse plate member 68 mounts a pair of vertically spaced rollers'72 for vertical movement in intermediate channel member 64, said pairsof rollers 7@ having axes of rotation transverse to the truck and saidpair of rollers 72 having axes of rotation longitudinal of the truck.Thus, the tractor and the load carrying units l2 and la are arranged forsome vertical parallel or articulated movement relative to each otherfor permitting the traction wheel 26, which supports the entire tractorunit, free to accommodate any depressions or obstacles in the line oftravel to maintain traction throughout. The pairs of rollers 7d and 72cooperate with the respective channel members 62 and 64 in order tomaintain the units 12 and 14 in proper alignment by resisting side andforward thrust, as well as torque forces, which would tend to separateor misalign the said units.

The lift truck 1t) has been described up to this point in rather generalterms. The details of construction of the lift truck as thus fardescribed are essentially conventional and form no part of the presentinvention except as certain portions thereof may appear in combinationWith remote control means to be described in detail hereinafter. For amore detailed disclosure of the powerhead 18, control handle 24 andassociated parts, reference may be had to US. Patents Nos. 2,762,444 and2,788,093, issued in the names of R. H. Gardner and D. S. Steinberg etal. on September 11, 1956 and April 9, 1957, respectively, and toassignees saies publication entitled Powrworker power, which carriesidentiiication No. T.C. 90-l057-l5M.

The Gardner patent is, in the main, directed to the manner of mountingthe drive head unit, including drive motor 19 and traction wheel Ztl, ona plurality of rollers mounted in a circular track formed by open ring71 of platform 2g so that the entire drive head unit may rotate withcontrol handle about a vertical axis for steering the truck.

The Steinberg et al. patent discloses a steering handle control,including brake means which is automatically applied to the drive motorwhenever the control handle is in either a vertical or horizon-talposition and which is released when the control handle is intermediatesuch positions. The brake structure which is intended to be utilized inthe present lift truck differs essentially from that of said latterpatent only in the substitution of an electrically motivated rotarysolenoid for the brake shoe control cam linkage of the patent. Thesolenoid performs the same function as the cam of the patent.

The details of the overall truck configuration, including mounting ofthe tractor and load carrying units one to the other, is fully disclosedin the co-pending U.S. patent application Ser. No. 727,481, now PatentNo. 2,959,235 issued Nov. 8, 196C iiled April 9, 1958 in the names ofDeville H. Hubbard, deceased by Martha A. Hubbard et al. (commonassignee).

A complete disclosure of the details of the construction of upright 32appears in the co-pending US. continuation-in-part patent applicationSer. No. 760,744, led on September 12, 1958 in the names of RussellHastings, Jr. et al. (common assignee).

Now referring in detail to the operators remote control station of myinvention, station 16 includes a vertically upstanding structure showngenerally at numeral 160 which is engageable by and supported upon fcrktines 40 for vertical movement in upright structure 32 with the forks.Generally, the structure is a fabricated construction and includes aprotected operators station, as shown in FIGURE l, forwardly of which isle cated, for example, a pair of vertically spaced roller beds 102 and104 upon which articles may be supported for subsequent discharge intoelevated stationary bins in a warehouse and the like. Of course, any oneof a variety of article supporting or handling devices may be supportedupon the fork tines forwardly of the remote operat'ors station.

Vertically extending hollow posts 1% and 1&3 are mounted upon oppositeside portions of carriage plate member 42 for housing electricalconduits which are adapted to variously connect remote operator controlmeans in circuit with one or more components of the lift truck,including a steer pump motor 110, a lift pump motor 112, the drive motor(armature) 19 and speed and directional controls (including the motorfield) 114 and 116 therefor, respectively, a steer pump motor controlcircuit 118, lift and lower control circuits 129 and 122 for the liftpump motor 112, a remote brake control circuit 124, forward and reversetravel control circuits 126 and 128, and high` speed circuit 130. Abattery 132 is adapted to supply electrical energy to all of theforegoing circuits. All of the conventional or normal controls of thevarious operating components of the lift truck; are located in thecontrol handle 24 and control box 26 thereof which provides a pluralityof manually operable switches for operating the truck in forward orreverse, and for lifting and lowering the fork tin in the maststructure. The remote steering control includes manually operabledirectional valve means 134 located on the post 11i/6 and connected tocontrol power steering means which will be fully described hereinafter.Remote travel control means 136 is also mounted upon post 106 andincludes manually operable forward and reverse switches 13S and 140which are `located in circuits 126 and 128, respectively. Mounted uponpost 168 at the opposite side of the truck is a control box 142 whichincludes manually operable switches 144 and 146 which are adapted tocontrol the lifting `and lowering operation of the lift cylinderconstruction of the upright 32. Other remote control means which areinterrelated automatically with one or more of the foregoing remotecontrols will be described hereinbelow.

As illustrated schematically in FGURE 3, all of the various foregoingcontrol circuits, both normal and remote, are connected with the battery132 by means of lead lines 14% and 15G. The lift pump motor 112 isadapted to be connected to drive a hydraulic lift pump for supplyingpressure uid to the lift cylinder 48 whenever a normally opened switch152 is closed. The switch 152 is energized to closed position by a coil154 whenever the remote switch 144- is closed or a normal switch 156 ofcontrol box 26 is closed. Of course, itis assumed that an ignitionswitch 1S-is closed permitting operation of various ones of the truckcomponents. The operator may thus lift himself to any selected elevationwithin the range of the mast 32 for performing necessary maintenancework and/ or for conveniently loading and unloading materials on andfrom the deviceltlti.

In order that the operator may lower the device 16% from the remotecontrol position a lowering switch 146 is provided, as aforesaid, which,when closed, energizes a coil 16d of a solenoid valve which causes thevalve to open the lift cylinder to a uid sump for permitting controlledexhaust of the fluid from the lift cylinder with consequent loweringmovement of the fork tines du. A normal switch control 162 is connectedin parallel with switch 146 and is located at handle control box 26.

It is conventional practice in powered hand trucks of the type disclosedherein to provide brake means at the drive motor which is normallyengaged. Thus, if an operator should leave the truck the control handle2d may be automatically returned to a vertical position wherein thebrakes are applied so that the truck cannot move without an operatorbeing in attendance. in order that the brakes be released it is requiredthat the control handle be moved by the operator to a position intermediate the vertical and horizontal positions thereof, for example,vwhereupon the brake is automatically released so that the drive moto-rmay be energized to mobilize the truck. I have provided a brakelsolenoid having a coil 164 in circuit 124 which, when' energized,causes the brake to be released. In operating thetruck in the normalmanner by means of control handle 24, movement of the control handle tothe aforesaid intermediate position causes a normally open brake switch166 to be closed which energizes brake solenoid coil 164, therebyreleasing the brake. When the truck is operated from the remote controlstation, however, itis apparent that the brake switch 166 will remainopen inasmuch as the control handle 24 is automatically maintained in avertical position wherein the brake solenoid is normally de-energizedwhich causes the brake to be applied.

Circuit 126 controls the iow speed forward operation of the drive motor.It includes a coil 168 which, when energized, closes a normally openswitch 176 and opens a normally closed switch 172 of the series eld 116of the drive motor, whereby the battery supplies energy through themotor armature and a low speed resistor 174 downwardly through theseries iield 116 causing the truck to be driven forwardly at low speed.Coil 168 may be energized by closing a switch 176 in circuit 126, theswitch 176 being located on the control box 26 of the control handle.Like vise, the truck may be driven at low speed in reverse by energizinga coil 17S which causes a normally open switch 136 to be closed and anormally closed switch 162 to be opened, whereby the energy supplied bythe battery through the armature and low speed resistor 171i moves inthe opposite direction or upwardly through the series field causing themotor to be driven in a reverse direction. Coil 178 may be energized byclosing manual switch 184 in circuit 123, which latter switch is alsolocated on control. box 26.

In order to operate the truck at high speed in a forward direction, asequence cont-actor switch 166, which is connected to switch 176, isclosed which causes a high speed coil 133 to be energized. Coil 183closes a normally open high speed switch 119i) in motor speed controlcircuit 1li:- in parallel Iwith the resistor 17d, and the motor is thenoperated at relatively high forward speed. A second switch 192 isconnected in parallel with switch 136 in high speed circuit 131i and isoperated in sequence, but subsequent to, low speed reverse controlswitch 154, whereby high speed reverse operation of the drive motor maybe utilized. However, it will he noted that brake switch 166 must beclosed before closure of either of switch units 176, or 13d, 192 will beeffective to energize the drive motor. ln other words, unless thecontrol handle 2d is in its intermediate position, switch 166 remainopen, the brake remains engaged, and the truck drive motor cannot beenergized. This arrangement affords a safety device which permitsoperation of the truck only after certain positive measures have beentaken by the operator.

A pair of brake solenoid switches 194 and 196 are con nected to switches132 and 146, respectively, and are 1ocated in lines 208 and 266 ofcircuit 124 which bly-passes brake switch 166. riherefore, the `brakecan be released from the remote station by closing either of switches194 or 196, subsequent to which switch 13S or 146, respectively, may beclosed to energize coils 168 or 178 for forward or reverse drive of thetruck respectively. It will be noted that a normally closed lift limitswitch 262 is located in a line 264 in that portion of circuits 126 and128 which includes remote control forward and reverse switches 13S and1de. The lift limit switch is also shown in FIGURE 2, it being securedto the rearward ange of one of the fixed upright channel sections ofupright 32 at a pre-selected elevation of, say, six feet. A projection`296 is connected at the lower end of the adjacent extensiie section ofthe upright in overlapping relation with switch 262. Thus, extension ofthe inner extensible section of the upright to an elevation of six feetwill trip switch 262 to an open position, thereby opening automaticallythe remote control portions of circuits 126 or 123 so that it will notbe possible to drive the truck either in forward or reverse from theremote control position when the predetermined elevation has beenexceeded. ln other words, closing either switch 138 or 14d will notenergize coils 16d or 173 if limit switch 202 is open. All other remotecontrols remain operative above said predetermined elevation; ie., theoperator may operate the brakes, steer the traction wheel, or extend theupright to maximum elevation. Ti e lift limit switch is utilized as asafety device which prohibits trave-l of the truck from the remotestation if the operator is elevated above 5 a predetermined safe height.it will also be understood that the truck may not be operated at highspeed from the remote station since the remote travel controls 138 andcannot energize high speed coil 133.

As was pointed out hereinabove, steering is normally accomplished byrotating control handle 24 which swings the traction wheel 26 and thedrive motor about the vertical axis thereof in track 74. A powersteering system has been devised which permits the truck to be steeredwhen the operator is located at the remote control station. A hydraulicboost cylinder assembly 226 is secured at its base end to a frame member222 of the tractor unit 12, and is pivotally connected at the piston rodend thereof to a lever member 22d which is secured to a normally freelyrotatable sleeve member 226. Extending downwardly just inwardly of theone frame member 66 and through openings in the platform 27, a spacermember 228, sleeve member 226 and a second sleeve member 227 is a shaft230 which is supported at its lower end in a. bearing 229. A sprocket232 is mounted on the upper end of shaft 236 above platform 27 and isdrivingly connected to a sprocket 233 of the drive motor assembly bymeans of a chain 235. The sleeve 227 is connected to shaft 236 by meansof a key 23d and is formed to provide on opposite sides of the upperedge thereof a groove 236 which is registrable with projection 238formed on opposite sides of the lower edge of sleeve 226, said grooveand projection together forming clutch means which when engaged connectpower cylinder 220 to shaft 236 for rotating sprocket 232 by way ofsleeves 226 and 227.

A foot lever 246 extends through an opening 242 in the one frame member66 and is pivotally mounted on a supporting member 24d; it extendslaterally outwardly of the battery compartment 22 and inwardly of theframe member to pivotally connect with a sleeve member 248 by means of ayoke and pin means 246. Sleeve 248 is slidable on shaft 236 and is urgeddownwardly thereon by means of a spring 25) mounted upon the shaftbetween sleeve members 227 and 246. A second spring member 252 is alsomounted on shaft 236 in an enlarged portion of the opening throughsleeve member 227 and between sleeve members 226 and 227.

When the foot pedal 2do is moved in a counterclockwise direction, asviewed in FIGURE 4, to a disengaged position, spring 256 elongatespermitting spring 252 to separate clutch members 236 and 228 of sleeves226 and 227. When the clutch is thus disengaged, energization of powercylinder 226 will rotate sleeve 226 freely on shaft 236 and eects nosteering action. However, when foot pedal 2d@ is actuated in a clockwisedirection to the solid line position illustrated in FGURE 4, spring 256is forced upwardly in compression with sleeve member 268 to actuatesleeve member 227 upwardly along shaft 23@ and engage ciutch members 236and 233. lf double-acting cylinder 226 is now energized for eitherextension or retraction of the piston rod thereof, rotation of sleeve226 will, through the clutch connection to sieeve 227, cause the lattersleeve to rotate with sleeve 226, which in turn actuates shaft 236 inrotation by means of the key connection 234 thereof to sleeve 227.Rotation of shaft 230 causes sprocket 232 to rotate, thereby rotatingthe drive motor and traction wheel through the sprocket and chainconnection 233, 23S. Steering of the truck in either direction may bethus effected by energizing power cylinder 22d to either extend orretract the piston rod thereof.

The steering control valve 134 is connected by hydraulic lines, notshown, intermediate the steering pump motor 111i and the power cylinderPump motor 1.16- is, of course, connected to a hydraulic sump, notshown, and is adapted to supply pressurized duid to the power cylinder226 through directional valve 134, the low pressure side of cylinder 226always being connected to the sump.

When the control valve l131i is located in its neutral position anormally open switch 262 (FIGURE 3) is open and the steer pump motor 116remains inactive. lf the 0perator should now move the directional leverin one direction, switch 262 is closed and communication is establishedbetween pump motor il@ and a selected end of power cylinder 22@ throughvalve control i3d. Closure of switch 262 energizes a coil Zed in circuitM8 of a steering pump switch 266, thereby closing switch 266 andenergizing pump motor liti. Assuming, of course, that the foot pedal24.16 is engaged, consequent energization of power cylinder 22d willcause the traction wheel 2t? to be turned in the selected direction rorsteering the truck.

It will be understood that steering of the truck can be effected innormal operation only by means of control handle 24 and with the footpedal 24@ disengaged. On the other hand, remote control steering can beeffected only by means of control valve i3d, power cylinder 22d andassociated mechanism, and when the foot pedal 240 is actuated to engagedposition. During such remote steering control handle 24 merely swingswith the drive motor and traction wheel to the right or to the left asthe truck is steered remotely, while remaining in a vertical position.

From the above it will now be understood that I have provided a remotecontrol system for lift trucks which can be utilized to perform allnormal truck functions, including driving, steering, braking, liftingand lowering, but with safety limitations on available speed and maximumfork elevation while the truck is being driven from the remote position.

`It will be understood that changes in construction and the arrangementof parts may be resorted to without departing from lthe field and scopeof my invention, and l intend to include all such variations, as fallwithin the scope of the appended claims, in this application in whichthe preferred form only of my invention has been disclosed.

I claim:

1. in a lift truck having a motor driven dirigible wheel, normal controlmeans located on the truck and connected to the wheel for steering same,and an extensible upright connected to the truck and supporting asecondary or remote control station thereon for elevating movement alongthe upright; remote control steering means comprising reversible motormeans connectible to the wheel for turning the wheel in either steeringdirection, clutch means selectively engaging and disengaging the motormeans with the wheel, the normal control means being movable to steerthe wheel when the motor means is disengaged frorn the wheel, and motorcontrol means located on the remote control station and operativelyconnected to the motor means for actuating same in a selected steeringdirection.

2. A lift truck as claimed in claim l wherein the dirigible wheel issteerable by said normal control means only when said clutch meansdisengages the motor means from the wheel and is steerable by saidremote control means only when said clutch means engages the motor meansand the wheel. i

3. A lift truck as claimed in claim l wherein said motor means comprisesa hydraulic power cylinder assembly connected to the frame of the lifttruck and through said clutch means, when the latter is engaged, to thedirigible wheel, said motor control means including directional controlvalve means connected to the hydraulic cylinder for operating same ineither direction from an elevated position on the remote controlstation.

4. A lift truck as claimed in claim 3 wherein the operative connectionbetween the hydraulic cylinder and dirigible wheel comprises an uprightrotatable shaft member supported upon the truck frame and connected tothe wheel by sprocket and chain means, a normally freely rotatablesleeve member on the shaft connected to the operating end of thehydraulic cylinder, a second sleeve means keyed to the shaft, engageableclutch means 'formed between said first and second sleeve members, and`a control member connected to the second sleeve member for actuatingsameV into clutching engagement Si with the first sleeve member,whereupon energization of the hydraulic cylinder assembly effectsrotation of said shaft with the first and second sleeve members torotate the wheel through the sprocket and chain means.

5. In a lift truck having a motor driven wheel, normal control meanslocated on the truck for edecting tractive movement of the wheel ineither a forward or a reverse direction, an extensible upright connectedto the truck, and an elevatable load carrying means supported on theupright; electrical control means associated with the normal controlmeansv for eecting elevating movement of the upright, and a remotecontrol station mounted upon the load carrying means and elevatabletherewith comprising operator controlled electrical means forcontrolling the elevation of the remote control station with the loadcarrving means on the upright, other operator controlled electricalmeans for operating the motor driven wheel either forward or reverse,and travel limit means operatively connected to the motor driven wheelfor deenergizing the wheel upon predetermined elevation of the upright.

6. A lift truck as claimed in claim 5l wherein said normal control meansfor driving the wheel in a forward or reverse direction includes low andhigh speed selection switches, and said remote control means for drivingthe wheel includes only low speed selection switches.

7. A lift truck as claimed in claim 5 wherein remote electrical brakecontrol means are associated with the remote forward and reverse travelcontrol means in such a manner that operation of the aforesaidelectrical brake and travel control means lirst operates to releasebrake means and then to energize the motor driven wheel for forward orreverse tractive movement.

8. A lift truck as claimed in claim 5 wherein said travel limit meanscomprises switch means connected to the upright.

9. ln a lift truck having a motor driven dirigible wheel, normal controlmeans located on the truck for effecting tractive movement of the wheelin a forward or a reverse direction, other normal control means locatedon the truck and connected to the wheel for steering same, and an eX-tensible upright connected to the truck and supporting a secondary orremote control station thereon for elevating movement along the upright;remote control steering means including reversible steering motor meansconnectible to the wheel for turning the wheel in either steeringdirection, means selectively engaging and disengaging said steeringmotor means with the wheel, the normal steering control means beingmovable to steer the wheel when the steering motor means is disengagedfrom the wheel, and remote'steering motor control means located on theremote control station and operatively connected to the steering motormeans for actuating same in a selected steering direction, electricalcontrol means associated with the normal tractive control means foreffecting elevating movement of the upright, remote operator controlledelectrical means controlling the elevation of the remote control stationon the upright, other remote operator controlled electrical means on theremote control station for operating the motor driven wheel in eitherforward or reverse, and travel limit means operatively connected to themotor driven wheel for cle-energizing the wheel upon predeterminedelevation of the remote control station.

l0. A lift truck as claimed in 9 wherein said means for selectivelyengaging and disengaging the steering motor means comprises clutch meanswhich permits said wheel to be steered by said normal steering controlmeans when the clutch means disengages thersteering motor means from thewheel and permits said wheel to be steered by said remote steeringcontrol means when the clutch means engages the motor means and thewheel.

ll. A lift truck as claimed in claim 9 wherein remote electrical brakecontrol means is associated with the remote operator controlled meansfor operating the motor driven wheel such that said remote electricalbrake and motor driven wheel control means operates in sequence to rstrelease the brake means and to then energize the driven wheel forforward or reverse tractive movement.

12. In a lift truck having a motor driven dirigible wheel, an extensibleupright connected to the truck and supporting a remote control stationfor elevating movement along the upright, and normal control and motivepower means located on the truck for steering the motor driven wheel,for driving said wheel selectively in forward and reverse rotation, forelevating said remote control station along the upright, and for brakingsaid wheel; remote control steering means connectible to the dirigiblewheel including means selectively engaging and disengaging the steeringmeans and control means located on the remote control stationoperatively connected to the remote steering means for actuating same in`a selected steering direction, remote operator control electrical meansoperating the motor driven wheel in either forward or reverse rotation,travel limit means operatively connected to the 10 motor driven wheelfor de-energizing the wheel upon predetermined elevation of the remotecontrol station in the upright, and remote electrical brake controlmeans associated with said remote forward and reverse driven wheelcontrol means such that said remote brake and driven wheel control meansoperates sequentially to rst release said brake means and to thenenergize the motor driven wheel for forward or reverse tractivemovement.

References Cited in the ile of this patent UNITED STATES PATENTS2,052,200 Logan Aug. 25, 1936 2,376,875 Honig May 29, 1945 2,402,579Ross June 25, 1946 2,592,091 Weaver Apr. 8, 1952 2,632,530 Wagner Mar,24, 1953 2,754,087 Johnson July 10, 1956 2,761,569 Iserman Sept. 4, 19562,787,278 Mitchell Apr. 2, 1957

